Finishing system with cyclically operable closure control

Abstract

A finishing machine is provided with a closure which is movable to selectively open or restrict a discharge opening for selectively discharging or retaining materials in the tub of the machine. A pneumatic bellows moves the closure toward a discharge restricting position when supplied with pressurized air. The pressure of the air supplied to the bellows is monitored, and if it exceeds a predetermined magnitude before the closure reaches a discharge restricting position indicating that an object has been trapped by the closure, the movement of the closure is stopped, reversed, and reinitiated to release the object and subsequently move the closure to a discharge restricting position.

What is claimed is: 
     
       1. A vibratory finishing machine comprising: a. a supporting frame structure;   b. a tub structure carried on said frame structure but free to vibrate relative to said frame structure;   c. a vibration producing mechanism operably connected to said tub structure to vibrate said tub structure;   d. discharging means for controllably discharging materials from said tub structure, including: i. opening means defining a discharge opening in communication with said tub structure;   ii. closure means movable toward and away from said opening means for selectively restricting the discharge of materials from said tub structure through said discharge opening to selectively retain and discharge materials in and from said tub structure;   iii. closure operator means connected to said closure means for moving said closure means toward and away from said opening means to selectively restrict the discharge of materials from said tub structure through said discharge opening during the operation of said machine;   iv. sensor means for sensing an object trapped between said closure means and said opening means; and,   v. control means responsive to said sensing means and being connected to said closure operator means for reversing the movement of said closure means toward said opening means when an object is trapped between said closure means and said opening means to release such object.     
     
     
       2. The vibratory finishing machine of claim 1 additionally including stop means for stopping the movement of said closure means toward said opening means when said closure means has reached a discharge restricting position spaced from said opening means. 
     
     
       3. The vibratory finishing machine of claim 2 wherein said stop means is adjustable to stop the movement of said closure means at a selected distance from said opening means. 
     
     
       4. The vibratory finishing machine of claim 1 wherein said control means includes a timing control to move said closure means toward and away from said opening means at predetermined intervals of time during the operation of the machine, whereby the retention time of workpieces within the tub is controlled by the timing control. 
     
     
       5. The vibratory finishing machine of claim 1 wherein said control means is additionally operable to initiate movement of said closure means toward said opening after said closure means has reversed direction to release such object. 
     
     
       6. The vibratory finishing machine of claim 5 wherein said control means includes time delay means for delaying by a predetermined interval of time the initiation of movement of said closure means toward said opening after said closure means has reversed direction to release such object. 
     
     
       7. The vibratory finishing machine of claim 1 wherein: a. said closure operator means includes a pneumatic structure operable when supplied with pressurized air to move said closure means toward said opening means; and   b. said control means includes pressure responsive means for sensing the pressure of pressurized air supplied to said pneumatic structure during the movement of said closure means toward said opening means, and for initiating the reversal of movement of said closure means when said pressure exceeds a predetermined value.   
     
     
       8. The vibratory finishing machine of claim 7 wherein said control means additionally includes second sensor means for sensing when said closure means has reached a position near said opening means and for disabling the operation of said pressure responsive means to permit said pressure to rise above said predetermined magnitude. 
     
     
       9. A continuous feed vibratory finishing machine comprising: a. a supporting structure resiliently supporting a tub together with means for vibrating said tub relative to the supporting structure;   b. charging means and discharging means arranged to introduce into and discharge from said tub at spaced regions of the tub such materials as workpieces and finishing media, whereby said machine is operable in a continuous feed mode;   c. said discharge means having wall portions defining a discharge opening in communication with said tub;   d. discharge rate control means including: i. means movable selectively toward and away from said discharge opening to selectively restrict the passage through said opening of workpieces from said tub;   ii. operator means connected to said movable means for effecting movement of said movable means;   iii. sensor means for sensing when an object has become trapped between said movable means and said discharge means;   iv. control means connected to said operator means for controlling the movement of said movable means toward and away from said discharge means to control the retention time of workpieces within the tub; and   v. said control means being operable to reverse and subsequently reinitiate the movement of said movable means toward said discharge means when an object is trapped between said movable means and said discharge means, whereby such object is free to move from between said movable means and said discharge means before said movable means is again moved toward said discharge means.     
     
     
       10. The vibratory finishing machine of claim 9 additionally including stop means for stopping the movement of said movable means toward said discharge opening when said movable means has reached a discharge restricting position spaced from such portions of said discharge means as define said discharge opening. 
     
     
       11. The vibratory finishing machine of claim 10 wherein said stop means is adjustable to stop the movement of said movable means at a selected distance from such portions of said discharge means as define said discharge opening. 
     
     
       12. The vibratory finishing machine of claim 9 wherein said control means includes programmable means operable to effect movement of said movable means in accordance with a preselected cycle of operation. 
     
     
       13. The vibratory finishing machine of claim 9 wherein said control means includes time delay means for delaying by a predetermined interval of time the initiation of movement of said movable means toward said discharge means after said movable means has reversed direction to release such object. 
     
     
       14. The vibratory finishing machine of claim 9 wherein: a. said operator means includes a pneumatic structure operable when supplied with pressurized air to move said movable means toward said discharge means; and   b. said control means includes pressure responsive means for sensing the pressure of pressurized air supplied to said pneumatic structure during the movement of said movable means toward said discharge means, and for initiating the reversal of movement of said movable means when said pressure exceeds a predetermined value before said movable means reaches a position near said discharge means.   
     
     
       15. The vibratory finishing machine of claim 14 wherein said control means additionally includes second sensor means for sensing when said movable means has reached a position near said discharge means and for disabling the operation of said pressure responsive means to permit said pressure to rise above said predetermined magnitude. 
     
     
       16. A process of finishing workpieces in the tub of a vibratory finishing machine having movable structure for selectively moving toward and away from a tub discharge opening to restrict and permit the discharge of materials from a finishing machine tub through the tub discharge opening, comprising the steps of: a. feeding workpieces and media into the tub at a location spaced from said discharge opening;   b. vibrating the tub to impart a motion to the workpieces and media to perform a finishing operation on the workpieces and to move the workpieces and media from said location toward the discharge opening;   c. moving said movable structure toward and away from said discharge opening in accordance with a predetermined cycle of operation to control the retention time of workpieces with the tub;   d. sensing when an object trapped has become trapped between said movable structure and the tub; and,   e. reversing and reinitiating the movement of said movable structure toward said discharge opening when an object has become trapped between said movable structure and the tub to release such object so movement of said movable structure to a position near said discharge opening can be effected.   
     
     
       17. The process of claim 16 additionally including the steps of subsequently moving said movable structure toward said discharge opening and stopping the movement of said movable structure at a position spaced from such portions of the tub as define said discharge opening. 
     
     
       18. The process of claim 17 wherein said step of stopping the movement of said movable movable structure is effected by bringing portions of said movable structure into engagement with a stop structure. 
     
     
       19. The process of claim 16 where the movement of said movable structure is effected in accordance with a preselected cycle of operation whereby the movement of said movable structure establishes an effectively uniform rate of discharge of materials from the tub. 
     
     
       20. In a vibratory finishing machine of the type including a tub for receiving workpieces and finishing media for vibration to effect a finishing action on the workpieces, the combination comprising: a. feeding means for feeding workpieces and media into the tub at a first location;   b. drive means for vibrating the tub to impart a motion to workpieces and media in the tub to perform a finishing operation on the workpieces and to move the workpieces and media from said first location toward a discharge location;   c. movable means for selectively restricting the passage of materials from said tub through a discharge opening formed in the tub at said discharge location in accordance with a predetermined cycle of operation to control the retention time of workpieces within the tub;   d. sensing means for sensing when an object has become trapped between said movable means and said tub; and   e. control means for reversing and re-initiating the movement of said movable means toward said opening when an object has become trapped between said movable means and the tub to release the trapped object so movement of said movable means to a position near said discharge opening can be effected.   
     
     
       21. The vibratory finishing machine of claim 20 additionally including stop structure positioned to engage and stop the movement of said movable means toward said discharge opening when said movable means has reached a predetermined position near said discharge opening. 
     
     
       22. The vibratory finishing machine of claim 21 wherein said position near said discharge opening is defined by said stop structure such that a space remains between said movable means and such portions of the tub as define said discharge opening, said space having a width sufficient to permit the passage therethrough of finishing media but being of insufficient width to permit the passage therethrough of workpieces. 
     
     
       23. The vibratory finishing machine of claim 22 wherein said stop structure is adjustable to stop the movement of said movable means at any one of a selected number of such space widths. 
     
     
       24. In a vibratory finishing machine of the type including a tub for receiving workpieces and finishing media for vibration to effect a finishing action on the workpieces, the combination comprising: a. feeding means for feeding such materials into the tub at a first location;   b. drive means for vibrating the tub to impart a finishing action to materials within the tub and to move such materials from said first location to a discharge location;   c. movable means for selectively restricting the passage of materials from said tub through a discharge opening formed in the tub at said discharge location in accordance with a predetermined cycle of operation to control the retention time of workpieces within the tub;   d. said movable means being movable from a position where the passage of materials through said opening is not substantially restricted to a position near to but spaced a predetermined distance from such portions of the tub as define said opening to restrict the flow of materials through said opening; and   e. adjustable stop means for adjusting said predetermined distance.   
     
     
       25. The apparatus of claim 24 wherein said adjustable stop means engages said movable means when said movable means reaches said position near said portions.